<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>demo3-7</title>
    <style>
        .classA{color:red;}
    </style>
</head>
<body>
    <script src="/js/vue.js"></script>
    <div id ="app">
     <div v-bind:class="{'classA':isRed}">我是v-bind指令，绑定class属性</div>
     <div v-bind:style="{fontSize: size +'px'}">我是v-bind指令，绑定style属性</div>
    </div>
    </body>
    <script>
     let app =new Vue({
     el:"#app",
      data:{
     isRed:true,
     size:20
      }
     })
    </script> 

</html>